The invention generally relates to a turbine installation, in particular a gas turbine installation.
By a gas turbine installation is meant hereafter an installation which includes a combustion chamber and a turbine located downstream of the combustion chamber and designated as a gas turbine.
In a combustion chamber of a gas turbine installation, a fuel gas is burnt in a gas space, and the hot gas generated at the same time is supplied to the turbine and flows through the latter. The flow path of the hot gas through the turbine is likewise designated hereafter as the gas space. The turbine has stationary guide vanes, which extend radially from outside into the gas space, and moving blades which are mounted on a shaft designated as a rotor and which extend radially outward from the rotor. As seen in the longitudinal direction of the turbine, the guide vanes and the moving blades engage one into the other in a tooth-like manner.
The turbine, as a rule, has a plurality of turbine stages, with a guide vane ring being arranged in each stage. Thus, a plurality of the guide vanes are arranged next to one another in the circumferential direction of the turbine. The individual guide vane rings are arranged successively in the axial direction.
Both at the combustion chamber and at the turbine, the gas space is conventionally lined with plate elements. At the combustion chamber, these are tiles, and at the turbine, the plate elements are formed by what are known as foot plates of the individual guide vanes.
The gas region of the combustion chamber and of the turbine is to be as leak-tight as possible. The aim is therefore to have insignificant leakage losses between the individual plate elements. In particular, leakage losses between two turbine stages are to be prevented.
As a result of the high temperature spans in the gas space, there is the problem that a seal has to absorb and bridge expansions of the individual plate elements, without the seal being appreciably impaired. This problem is aggravated by the fact that neither the tiles nor the foot plates of the guide vanes are fastened at their edge regions to adjacent plate elements, so that the plate edges are to a greater or lesser extent free and undergo bending as a result of thermal expansion. The tiles, for example, are, as a rule, fastened in their center and bend approximately spherically under thermal load. A seal must therefore allow both axial and radial movability, also because the combustion chamber and the turbine are designed conically in the axial direction.
In a conventional seal, the foot plates are provided in the region of the turbine with a groove on their end face, a sealing sheet being inserted into the grooves of two foot plates of guide vanes of adjacent turbine stages. Where the end-face grooves are concerned, the axial and radial movability of the foot plates is achieved in that the grooves have oblique side walls. However, grooves of this kind are highly complicated in production terms. Moreover, a seal of this kind is relatively leaky, since a varyingly rapid thermal expansion behavior of the foot plates and of what is known as the turbine guide vane carrier to which they are fastened must be taken into account.
To be precise, when the turbine is started up, the foot plates expand more rapidly, so that a leakage gap between the foot plates is initially closed. The leakage gap opens again when the turbine guide vane carrier has expanded according to the temperature.
With regard to the tiles in the combustion chamber, there is additionally the problem that, because they bend spherically, such a sealing sheet is sometimes subjected to shearing load until it fails.
An object on which an embodiment of the invention is based, is to make it possible to have a seal which overcomes at least one of the disadvantages described. The object may be achieved, according to an embodiment of the invention, by a turbine installation, in particular a gas turbine installation, with a gas space which is outwardly delimited via plate elements contiguous to one another. A sealing element is assigned in each case to plate elements adjacent to one another and connecting these to one another in a staple-like manner on their rear sides facing away from the gas space.
An advantage is seen in the staple-like configuration of the sealing element. The sealing element thus spans the two plate elements. Under thermal expansions, the sealing element follows the plate elements, without opening up a gap. The seal produced by the sealing element is therefore largely unaffected by thermal expansions.
In order to ensure as good a seal as possible, even under all-round thermal expansions, the sealing element preferably allows a movability of the plate elements both in the axial and in the radial direction. The sealing element may therefore be designed, in particular, to be elastic both in the axial and in the radial direction. By axial direction, what is meant is an expansion in the longitudinal direction of the turbine installation and by radial direction, it means an expansion perpendicular to the longitudinal axis.
Preferably, the sealing element has two limbs which engage in each case into a groove of plate elements adjacent to one another. This makes it possible to have a fastening of the sealing elements which is simple to implement in production terms.
Preferably, the groove extends from the rear side of the respective plate element into the latter, essentially radially. The limbs therefore project radially outward from the grooves. This configuration of the groove allows simple production and, in particular, high accuracy, for example by grinding or erosion. An advantage of the arrangement on the rear side is to be seen in that the groove does not have to be of a special shape with regard to the problem of thermal expansions. The groove and sealing element can therefore be adapted very accurately to one another, so that very small leakage gaps are achieved.
In order to make it possible to have a simple procedure for mounting the plate elements in the turbine installation, the sealing element is preferably of multipart construction.
In this case, preferably, the limbs of the multipart sealing element overlap one another over a common circumferential length. This circumferential length is in this case dimensioned sufficiently large essentially to avoid leakages.
In a preferred embodiment, the sealing element is of U-shaped design, this being simple to implement both in production terms and in assembly terms.
In order to achieve a high expandability of the sealing element, the latter has a wavy structure in the manner of a concertina in order to absorb expansions.
Expediently, the sealing element has this wavy structure in a plurality of directions, so that it can absorb expansions in different directions. In particular, the sealing element has a configuration in the form of a double S.
In a preferred embodiment, the sealing element is arranged between adjacent tiles of a combustion chamber. Reliable sealing between the tiles is consequently achieved, even when these bend spherically as a result of thermal load.
According to a particularly preferred embodiment, the sealing element is arranged between the foot plates of adjacent guide vanes of a turbine, specifically, in particular, between the foot plates of guide vanes of adjacent turbine stages.
The individual foot plates are accordingly connected to one another in the axial or the longitudinal direction of the turbine via staple-like sealing elements.
In order to achieve simple mounting of the plate elements, in particular of the foot plates, and at the same time good sealing of the plate elements both in the circumferential direction and in the axial direction between adjacent turbine stages, preferably, the staple-like sealing element described is provided for sealing in the axial direction and a further sealing element is provided for sealing in the circumferential direction. Depending on the direction, therefore, and in particular for assembly reasons, differently designed sealing elements are used.
The further sealing element in this case preferably has a reception region, into which the plate elements extend. In particular, the sealing element is designed with an H-shaped cross section. The fundamental idea of this configuration is to be seen in the reversal of a conventional sealing principle, in which a sealing sheet is introduced into corresponding end-face grooves of the foot plates. To be precise, this, as a rule, necessitates a reinforcement of the edge of the foot plates in the groove region. This presents problems with regard to an effective cooling of the foot plates, since, on account of the different material thicknesses, a uniform cooling can be implemented only with difficulty and thermal stresses may occur. In this case, in a reversal of this sealing principle, the sealing sheet is not inserted into the foot plates but, instead, the foot plates are introduced into the sealing element. This avoids the need for a reinforcement of the edge region of the foot plate. Coolability is thus simplified and the foot plate is cooled homogeneously in all regions, so that no thermal stresses occur.